1. Field of the Invention
The present invention relates to a process of anodic bonding between substrates and particularly to a method of producing an ink-jet print head which can be mounted in an electronic instrument such as a printer, a word processor, a facsimile machine, a plotter or the like.
2. Description of the Related Art
Various electric instruments include an ink-jet print head which functions as part of the printing mechanism thereof. There is known Kyser type of ink-jet print head. As shown in FIGS. 1 to 3, such a type of ink-jet print head generally comprises a head base 50 in which an array of individual ink passages 51 are formed. As best seen from FIG. 3, each of the individual ink passages 51 comprises an ink supply passage 51a, a pressure chamber 51b and a nozzle 51c. A vibrating plate 60 is joined over the top of the head base 50 and includes a plurality of piezoelectric elements 70 mounted thereon, each of which is positioned corresponding to the respective one of the pressure chambers 51b in the individual ink passages 51. When an electric field is applied to one of the piezoelectric elements 70 according to printing information, that piezoelectric element 70 is displaced. The displacement of the piezoelectric element 70 moves the corresponding part of the vibrating plate 60 to apply an instantaneous pressure to the ink which in turn is extruded from the individual ink passage 51 through its nozzle 51c. The extruded ink is thus sprayed toward a printing sheet.
In producing the Kyser type print head, the head base and vibrating plate 50, 60 are frequently formed of glass. It is customary that after the individual ink passages 51 have been formed on the glass head base 50, the glass vibrating plate 60 is adhered to the head base 50 using any suitable adhesive.
It is, however, difficult to apply the adhesive onto the substrate (the head base and vibrating plate 50, 60) with a thickness equal to or less than a certain level. In addition, the adhesive has a fluidity. For such reasons, the adhesive tends to flow into the individual ink passages 51 during the joining step, resulting in reduction of the width in the individual ink passages 51. This frequently causes the flow of ink to be disturbed or partially blocked in the individual ink passages on use of the ink-jet print head. Particularly, narrower ink supply passages and nozzles 51a, 51c connected to the individual ink passages 51 may be very easily blocked by the adhesive used, resulting in complete blockage of ink in the individual ink passages.